Mumbai, July 9 (IANS) Amitabh Bachchan and R. Balki had a fruitful association in unique love story "Cheeni Kum" and "Paa", a film on progeria. Now they have teamed up for "Shamitabh" and the megastar says that like their previous projects this one too is "out of the ordinary" and "challenging".

"Each one of Balki's films with me have been novel, out of the ordinary and most challenging. 'Shamitabh' is no different," said Big B when asked about how different is the experience of working with Balki in "Shamitabh".

Currently they are shooting in Europe and the 71-year-old said that the experience so far has been "exhilarating".

When asked if it is a coincidence that the film's title "Shamitabh" is very close to his own name, he said: "I do not have the liberty or the permission to reveal that yet, but on seeing the film there shall be greater clarity."

"Shamitabh" also marks the debut of Kamal Haasan and Sarika's daughter Akshara in filmdom. Southern star Dhanush, who is a big fan of Amitabh, too features in it.

This will be his second Hindi film after the hit "Raanjhanaa" and Big B describes his young co-star as "an exceptional artist".

"He enjoys a huge fan and star following in his own territory in South, as well as in the project that he did in Hindi in Mumbai. I am not aware of him being an unabashed fan of mine, quite the contrary.

"Akshara's is a first effort, which does not look like a first," he said.

Apart from "Shamitabh", Amitabh has said yes to "Shoojit Sircar's 'Piku'."

"Vidhu Vinod Chopra's production directed by Bejoy Nambiar, and a few others have been green lighted. Once I get closer to their schedules, I shall be in a better position to talk of them," he said.